The localized multicast approach reduces expended network resources by limiting transmissions to a geographic area defined by the radio coverage area of a base transceiver station or even smaller areas as defined by antenna coverage sectors of the base transceiver station. Multicast services in general are described in various standards such as the Third Generation Partnership Project (3GPP), Universal Mobile Telephone System (UMTS) standards.
Localized multicast is likewise generally described in the UMTS standards. The UMTS standards, Release 6, define in general, architectures and methods of operation such as a counting procedure for Multimedia Broadcast, Multicast Service (MBMS) whereby the network learns the status of mobile devices in each cell and configures Radio Bearers (RBs) based upon the learned status information.
Two modes of operation are employed in the standards, namely, Point-to-Point (PTP) and Point-to-Multipoint (PTM). Under counting procedures, coverage areas having less than a preset number of users, employ PTP operation which requires setup of RBs individually per user. Conversely, coverage areas having at least the preset number of users will employ PTM for MBMS delivery wherein individual RBs are not required.
For MBMS delivery using PTM, it is desirable for mobile stations, also referred to as “User Equipment” (UEs), to employ macro-diversity, that is, to employ selection combining or soft combining of multiple signal transmissions.
In the case of selection combining, the “Protocol Data Units” (PDUs) from two, or more than two, cells should be generated in the same manner, although they need not be transmitted simultaneously. For soft combining, the PDUs from two cells should likewise be generated in the same manner and also should be transmitted simultaneously.
However, the current Enhanced Universal Terrestrial Radio Access Network (UTRAN) architecture incorporates cells (“Base Transceiver Stations” (BTS) or “Node Bs”), which provide scheduling and segmentation and reassembly (SAR) functions independently of any central point of control. Such architecture does not account for the UE's need to employ macro-diversity for MBMS PTM as discussed above.